This work will involve investigations into the role which the sodium pump may play in the cellular action of insulin. The principal approach will involve studies on intact muscle cells from both normal and diabetic animals. The first objective will be to investigate the mechanism whereby insulin increases the intracellular pH, pHi, of muscle and to determine if the action of insulin upon the sodium pump plays any role in this action. A second objective will be to determine if the stimulation of glycolysis by this effect is mediated by changes in intracellular pH, ATP, ADP, or P. A third objective will be to see if insulin increases the number of sodium pump sites and/or if the affinity of these pumps of ouabain is changed. A fourth objective will be to determine if the diabetic state in experimental animals is associated with evidence of decreased sodium pump activity. The experiments will be conducted on frog skeletal muscle (sartorius) and upon rat skeletal muscle (soleus) with the muscle from one leg serving as a paired control for the other.